Mold assembly

ABSTRACT

A mold assembly for insert-molding a heterogeneous object includes an upper mold and a lower mold. The upper mold includes a cavity for accommodating an insert object. The lower mold includes a rigid body and a resilient contact member for resting the insert object. The resilient contact member absorbs dimensional variations of the insert object during the insert molding process.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. application Ser. No. 13/117,110 filed May 26,2011, which claims the benefit of U.S. provisional application No.61/428,822 filed Dec. 30, 2010. The above-mentioned applications areincluded in their entirety herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a mold assembly, and morespecifically to a mold assembly having at least a resilient contactmember particularly suited for the art of applying an insert-molding toa heterogeneous object.

2. Description of the Prior Art

FIG. 1 and FIG. 2 are cross-sectional views of a conventional moldassembly. A rigid mold assembly 100 is used for insert-molding a part 10such as a heterogeneous object, wherein the material of the rigid moldassembly 100 may be metal such as aluminum, iron, steel etc. The rigidmold assembly 100 has an upper mold 110 and a lower mold 120, and aninner space 130 is formed between the upper mold 110 and the lower mold120. The part 10 may include a non-elastic part 2 and an elastic part 4combined with the non-elastic part 2, wherein the non-elastic part 2 maybe non-polymer elastomer such as metal, ceramic, glass, plastic etc. andthe materials of the elastic part 4 may be polymer elastomer such assynthetic rubbers, silicon gel etc. A method of forming the part 10 maybe: disposing the non-elastic part 2 in the inner space 130, theninjecting the polymer elastomer into the inner space 130 and curing thepolymer elastomer, at which point the part 10 is completed.

The drawback of the above prior art method is: clearance or interferencebetween the part 10 and the rigid mold assembly 100 occurs due toself-dimensional variation of the non-elastic part 2, deformation of thenon-elastic part 2 caused by thermal expansion, or hardness of thenon-elastic part 2. For example, as shown in the circular, enlarged viewof FIG. 1, when the size of the non-elastic part 2 is too small, the gap140 occurs between the non-elastic part 2 and the lower mold 120. Thegap 140 will lead to overflow of the injected polymer elastomer whichmay be difficult to clean in post processing. As a result, theprocessing yield is reduced. Furthermore, as shown in the circular,enlarged view of FIG. 2, when the size of the non-elastic part 2 is toobig, interference occurs between the non-elastic part 2 and the lowermold 120, thereby damaging the appearance of the non-elastic part 2. Theinterference between the part 10 and rigid mold assembly 100 can alsooccur due to thermal expansion during the insert-molding process, sothat the appearance of the part 10 may be damaged.

FIG. 3 is a cross-sectional view of another conventional mold assembly.The elastic part 4 is combined on two sides of the non-elastic part 2,and the upper side A1 and the lower side A2 of the non-elastic part 2respectively contact the upper mold 110 and the lower mold 120. Due tothe lack of resilience and deformation capability of the non-elasticpart 2, upper mold 110, and lower mold 120, the non-elastic part 2 iseasily crushed or damaged by the upper mold 110 and the lower mold 120when the size of the non-elastic part 2 is too big. On the other hand,as shown in FIG. 4, when the size of the non-elastic part 2 is toosmall, overflow of the polymer elastomer will occur after mold-locking.

Therefore, an improved mold assembly is needed, wherein a part havingdimensional accuracy is formed without hurting the structure or theappearance of the part.

SUMMARY OF THE INVENTION

The present invention provides a mold assembly having at least aresilient contact member to solve the problems and the drawbacks of theprior art.

The present invention provides a mold assembly for insert-molding aheterogeneous object, including an upper mold and a lower mold. Theupper mold includes a cavity for accommodating an insert object. Thelower mold includes a rigid body and a resilient contact member. Theinsert object is disposed on the resilient contact member during aninsert molding process, such that the resilient contact member absorbs adimensional variation of the insert object during the insert moldingprocess.

The present invention provides a mold assembly, including an upper moldand a lower mold. The upper mold includes a first rigid body and a firstresilient contact member. The lower mold includes a second rigid bodyand a second resilient contact member. The upper mold and the lowermold, when combined together, define an inner space for accommodating aninsert object, wherein the insert object contacts both the firstresilient contact member and the second resilient contact member,thereby absorbing a dimensional variation of the insert object.

According to the above, the present invention provides a mold assemblyhaving at least a resilient contact member using for contacting aninsert object accommodated in the mold assembly, such that the insertobject does not contact the rigid part of the mold assembly. As apolymer elastomer injected into the mold assembly to form aheterogeneous object forming by bonding the insert object with polymerelastomer, overflow of the polymer elastomer or damage of the insertobject caused by dimensional variation of the insert object will notoccur.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and FIG. 2 are cross-sectional views of a conventional moldassembly.

FIG. 3 and FIG. 4 are cross-sectional views of another conventional moldassembly.

FIG. 5 depicts a cross-sectional view of a mold assembly in accordancewith a first embodiment of the present invention.

FIG. 6 depicts a cross-sectional view of the mold assembly of FIG. 5after die locking.

FIG. 7 depicts a three-dimensional side view of a heterogeneous objectin accordance with an embodiment of the present invention.

FIG. 8 depicts a combination principle of a primer in accordance with anembodiment of the present invention.

FIG. 9 depicts a cross-sectional view of a mold assembly in accordancewith a second embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 5 depicts a cross-sectional view of a mold assembly in accordancewith a first embodiment of the present invention. FIG. 6 depicts across-sectional view of the mold assembly of FIG. 5 after die locking.As shown in FIG. 5 and FIG. 6, the mold assembly 200 includes an uppermold 210 and a lower mold 220. The lower mold 220 includes a rigid body222 and a resilient contact member 224 located on an inner side S1 ofthe rigid body 222. The upper mold 210 includes a cavity 212 foraccommodating an insert object 24. The insert object 24 is disposed onthe resilient contact member 224. The upper mold 210 and the lower mold220, when combined together, define an inner space 230. The moldassembly 200 is not limited to the upper mold 210 and the lower mold 220and the mold numbers of the mold assembly 200 depend on actual demands.The relative position of the upper mold 210 and the lower mold 220 canalso change according to requirements. The polymer elastomer 22 isinjected into the inner space 230 to fill the inner space 230. After thepolymer elastomer 22 is cured, the polymer elastomer 22 bonds with theinsert object 24 to form a heterogeneous object 20. The dimensionalvariation of the insert object 24 can be absorbed during aninsert-molding process due to the material of the resilient contactmember 224 being an elastic material, wherein the dimensional variationof the insert object 24 may be generated during manufacturing processesor generated by expansion and contraction during insert-moldingprocesses. When the size of the insert object 24 is too small, theresilience of the resilient contact member 224 means the insert object24 allows slightly pressing forces to fill the space without anyclearance, therefore avoiding overflow of the injected polymer elastomer22. In contrast, when the size of the insert object 24 is too big, theinsert object 24 can also allow more deformation than when contactingwith rigid materials because of the compression characteristic of theresilient contact member 224, therefore the dimensional variation of theinsert object 24 which can cause interference is absorbed withoutdamaging the structure or the appearance of the insert object 24. As aresult, the present invention provides the mold assembly 200 forinsert-molding a heterogeneous object 20 that can improve the processingyield.

Specifically, the materials of the upper mold 210 and the rigid body 222may be rigid materials such as aluminum, copper, metal alloys etc. In apreferred embodiment, the upper mold 210 and the rigid body 222 arehigh-temperature proof materials that can resist the molding temperatureduring insert-molding process. The resilient contact member 224 and thepolymer elastomer 22 are composed of polymer elastic materials such assilica gel, plastic, synthetic rubber, resins etc. It should be notedthat the resilient contact member 224 and the polymer elastomer 22 arecomposed of different materials so that the resilient contact member 224and the polymer elastomer 22 will not combine to form one piece duringthe insert molding process. For example, the polymer elastomer 22 may becomposed of silica gel while the resilient contact member 224 iscomposed of a synthetic rubber, or the polymer elastomer 22 may becomposed of a synthetic rubber while the resilient contact member 224 iscomposed of silica gel. In other words, the polymer elastomer 22 and theresilient contact member 224 cannot both be silica gel or syntheticrubbers at the same time. The reason is that the polymer elastomer 22injected into molds during the insert-molding process is molten, so itwill combine with the insert object 24 after curing. As a result, thepolymer elastomer 22 and the insert object 24 would melt and combineinto one piece, leading to the heterogeneous object 20 being unable tobe mold released after molding.

FIG. 7 depicts a three-dimensional side view of a heterogeneous objectin accordance with an embodiment of the present invention. In thisembodiment, the heterogeneous object 20 may be a notebook or cell phonehaving a polymer elastomer 22 and an insert object 24, wherein theinsert object 24 may be a portion of a case of a notebook or a cellphone, and the polymer elastomer 22 may be a soft film covering thecase. In other embodiments, the heterogeneous object 20 may be otherparts and is not limited thereto. The patterned surface S2 of thepolymer elastomer 22 tightly combines with the corresponding patternedsurface S3 of the insert object 24, wherein the material of the polymerelastomer 22 may be a polymer elastic material such as silicon gel,rubber, etc., and the material of the insert object 24 may be anon-polymer elastic material such as aluminum alloy, plastic steel,plastic, ceramic or glass. The relative position of the polymerelastomer 22 and the insert object 24 may change as long as thematerials of the polymer elastomer 22 and the insert object 24 aredifferent. Additionally, the shape, the size and the numbers of thepattern P using for fixing and bonding the polymer elastomer 22 with theinsert object 24 depend upon practical considerations.

As shown in FIG. 6, a profile of a contact surface S4 of the resilientcontact member 224 conforms to a bottom surface S5 of the insert object24. That is, the resilient contact member 224 and the insert object 24can be combined with the largest contact area, therefore sliding, gapsor interference between the resilient contact member 224 and the insertobject 24 leading to overflow of the polymer elastomer 22 or damage ofthe insert object 24 during insert molding process is avoided. In apreferred embodiment, the insert object 24 does not contact the uppermold 210 or the rigid body 222, so that clearance or interferencebetween the rigid materials of the insert object 24, the upper mold 210and the rigid body 222 caused by lack of resilience and deformation ofthe insert object 24, the upper mold 210 and the rigid body 222 isavoided.

In a preferred embodiment, the resilient contact member 224 may be fixedon the inner side S1 of the rigid body 222 for avoiding misalignment ofthe insert object 24 above the resilient contact member 224 due todislocation of the resilient contact member 224 caused by expansion andcontraction in a high temperature process or temperature changingenvironment. Specifically, the resilient contact member 224 can bondwith the rigid body 222 via a primer. One kind of combination principleof the primer is shown in FIG. 8, wherein —OH bonding generated aftersilane primers hydrolyzing can bond with non-polymer elastomers such asmetal, ceramic, glass, plastic etc., so that the resilient contactmember 224 and the rigid body 222 can combine with high bonding strengthand still have good dimensional stability after repeated operations.Durability of the mold assembly 200 improves significantly. It should benoted that the present invention is not limited to using primers betweenthe resilient contact member 224 and the rigid body 222. As the moldingshape is not complicated, the resilient contact member 224 having hightemperature resistance can be formed first and then embedded into themold assembly 200 as a portion of the mold assembly 200. The benefit ofthe forming method is that the resilient contact member 224 can bereplaced faster than in the prior art. Otherwise, the insert object 24and the polymer elastomer 22 may be combined via the primer shown inFIG. 6. In doing so, the insert object 24 and the polymer elastomer 22can be formed stably and the size accuracy of the insert object 24 andthe polymer elastomer 22 can be maintained after molding. Due to thestrong combination between the insert object 24 and the polymerelastomer 22, the durability of the heterogeneous object 20 improves. Itis further mentioned herein that the primer bonding the resilientcontact member 224 and the rigid body 222 is not always the same as theprimer bonding the insert object 24 and the polymer elastomer 22, anddepends on the characteristics of the materials of these components.

FIG. 9 depicts a cross-sectional view of a mold assembly in accordancewith a second embodiment of the present invention. As shown in FIG. 9,the mold assembly 300 includes an upper mold 310 and a lower mold 320.The upper mold 310 includes a first rigid body 312 and a first resilientcontact member 314, and the lower mold 320 includes a second rigid body322 and a second resilient contact member 324. In this embodiment, theupper mold 310 and the lower mold 320 have upper and lower symmetry, butthey also can be a non-symmetrical structure in another embodiment. Themold assembly 300 is not limited to including only the upper mold 310and the lower mold 320, and the mold numbers of the mold assembly 300may change. The relative position of the upper mold 310 and the lowermold 320 can also change. As the upper mold 310 and the lower mold 320are combined together, an inner space 330 for accommodating an insertobject 24′ is defined. After the insert object 24′ is disposed in theinner space 330, a polymer elastomer 22′ is injected into the innerspace 330 to fill the remaining space of the inner space 330, so thatthe polymer elastomer 22′bonds with the insert object 24′ to form aheterogeneous object 20′. In this embodiment, the first resilientcontact member 314 and the second resilient contact member 324 clamp theinsert object 24′ thereby absorbing dimensional variations of the insertobject 24′. For example, when the size of the insert object 24′ is toosmall so that clearance is generated between the upper mold 310 and theinsert object 24′ or between the lower mold 320 and the insert object24′, or when the insert object 24′ is too big so that interference isgenerated between the upper mold 310 and the insert object 24′ orbetween the lower mold 320 and the insert object 24′, the overflow ofthe polymer elastomer 22′ or the damage of the insert object 24′ areavoided because of the resilience of the first resilient contact member314 and the second resilient contact member 324.

Likewise, the first rigid body 312 and the second rigid body 322 may becomposed of rigid materials such as metal, alloy etc. The insert object24′ includes non-polymer materials such as metal, plastic, ceramic,glass etc. The first resilient contact member 314, the second resilientcontact member 324 and the polymer elastomer 22′ may be polymer elasticmaterials such as silicon gel, plastic, synthetic rubber, resin etc. Thefirst resilient contact member 314 and the second resilient contactmember 324 may be composed of different materials, and the first rigidbody 312 and the second rigid body 322 may be composed of differentmaterials as well, depending upon requirements. It should be noted thatthe materials of the first resilient contact member 314 and the secondresilient contact member 324 are different from the materials of thepolymer elastomer 22′, because the polymer elastomer 22′ respectivelycontacts the first resilient contact member 314 and the second resilientcontact member 324. For example, the polymer elastomer 22′ may becomposed of silicon gel while the first and the second resilient contactmember 314, 324 are composed of synthetic rubber, or the polymerelastomer 22′ may be composed of synthetic rubber while the first andthe second resilient contact member 314, 324 are composed of silicongel, but the invention is not limited thereto. The reason is that thepolymer elastomer 22′ injected into molds during the insert-moldingprocess is molten, so it will combine with the first resilient contactmember 314 or the second resilient contact member 324 as the material ofthe polymer elastomer 22′ is the same as the materials of the firstresilient contact member 314 or the second resilient contact member 324.As a result, the polymer elastomer 22′ and the first resilient contactmember 314 or the second resilient contact member 324 will melt andcombine into one piece, leading to the heterogeneous object 20′ beingunable to be mold released after molding.

In a preferred embodiment, the profile of the first resilient contactmember 314 and the second resilient contact member 324 conforms to theinterface S6, S7 of the insert object 24′ for fixing the relativeposition of the insert object 24′ and the first and the second resilientcontact member 314, 324. This avoids clearance between the firstresilient contact member 314 and the insert object 24′ or the secondresilient contact member 324 and the insert object 24′, and avoidsinterference between the first rigid body 312 and the insert object 24′or the second rigid body 322 and the insert object 24′ caused by theslide of the insert object 24′.

In a preferred embodiment, the first resilient contact member 314 isfixed on the inner side S8 of the first rigid body 312, or the secondresilient contact member 324 is fixed on the inner side S9 of the secondrigid body 322. Therefore, misalignment of the insert object 24 isavoided due to dislocation of the first resilient contact member 314 orthe second resilient contact member 324 caused by expansion andcontraction in a high temperature process or temperature changingenvironment. The first resilient contact member 314 or the secondresilient contact member 324 can respectively bond with the first rigidbody 312 or the second rigid body 322 via a primer, wherein the primermakes the first resilient contact member 314 or the second resilientcontact member 324 combine with the first rigid body 312 or the secondrigid body 322 with high bonding strength while still retaining gooddimensional stability after repeated operations. Thereby, durability ofthe mold assembly 300 is improved. It should be noted that the presentinvention is not limited to using primers between the first resilientcontact member 314 or the second resilient contact member 324 and thefirst rigid body 312 or the second rigid body 322. The insert object 24′and the polymer elastomer 22′ may also be combined by the primer shownin FIG. 6. Furthermore, the primer which bonds the first resilientcontact member 314 or the second resilient contact member 324 to thefirst rigid body 312 or the second rigid body 322 is not always thesame, depending on the characteristics of the materials used.

In another preferred embodiment, the insert object 24′ does not contactthe first rigid body 312 or the second rigid body 322, so that clearanceor interference caused by the lack of resilience and deformationcapability of the rigid materials can be avoided.

According to the above, the present invention provides a mold assemblyhaving an upper mold and a lower mold. At least a resilient contactmember, more specifically a polymer resilient contact member, located onthe inner side of the upper mold or the lower mold is used forcontacting an insert object accommodated in the mold assembly. In thisway, the insert object does not directly contact the rigid materialparts of the mold assembly, so that overflow of the polymer elastomer ordamage of the insert object caused by clearance or interferencegenerated by dimensional variations of the insert object is avoided. Thepolymer elastomer is injected into the mold assembly and bonds with aninsert object to form a heterogeneous object, wherein the polymerresilient contact member and the injected polymer elastomer are made ofdifferent materials, which prevents the polymer resilient contact memberand the injected polymer elastomer from combining into one piece andcausing difficulty in mold releasing. The present invention alsoprovides primers used for combining the polymer elastomer with theinsert object and combining the polymer resilient contact member withthe rigid body, which enables the two to have a strong bonding betweenthem, thereby improving durability of the parts or the molds.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A mold assembly, comprising: an upper moldcomprising a first rigid body and a first resilient contact member; anda lower mold comprising a second rigid body and a second resilientcontact member, wherein the upper mold and the lower mold, when combinedtogether, define an inner space for accommodating an insert object,wherein the insert object contacts both the first resilient contactmember and the second resilient contact member, thereby absorbingdimensional variations of the insert object.
 2. The mold assemblyaccording to claim 1, wherein the first resilient contact member isfixed on an inner side of the first rigid body.
 3. The mold assemblyaccording to claim 1, wherein the second resilient contact member isfixed on an inner side of the second rigid body.
 4. The mold assemblyaccording to claim 1, wherein a polymer elastomer, which is injectedinto the inner spacer, bonds with the insert object to form theheterogeneous object.
 5. The mold assembly according to claim 4, whereinthe polymer elastomer is composed of a material that is different fromthe first and the second resilient contact members.
 6. The mold assemblyaccording to claim 5, wherein the polymer elastomer is composed ofsilica gel and the first and the second resilient contact members arecomposed of synthetic rubbers.
 7. The mold assembly according to claim5, wherein the polymer elastomer is composed of a synthetic rubber andthe first and the second resilient contact members are composed ofsilica gels.
 8. The mold assembly according to claim 1, wherein theinsert object does not contact the rigid body.
 9. The mold assemblyaccording to claim 1, wherein the insert object comprises metal,plastic, ceramic or glass.